The present invention relates to an improved method and apparatus for moving bottom sand and other sediment to provide a change in the bottom profile at a specific location in the bottom of a body of water. The present invention accomplishes its movement of such material by utilizing propellers on a vessel at the water surface and movable plates to control the discharge from the propellers to both loosen the material and to transport the material away from its initial location.
The use of propellers has been tried prior to the present invention with limited success. The publication "AGITATION DREDGING: LESSONS AND GUIDELINES FROM PAST PROJECTS" by Thomas W. Richardson, Hydraulics Laboratory, Vicksburg, Miss., July 1984 and identified as 85 01 29 015. This article outlines the testing done by the Department of the Army, U.S. Army Corps of Engineers of the use of ships propellers and water jets in moving bottom material from preselected locations on the bottom of bodies of water. On page A18 they include a picture of a vessel named the "Salvage Chief" which has a hydraulically operated S-shaped deflector door which was used to deflect the prop wash from its propellers downward, to thereby concentrate and direct the flow and produce some sediment transport by induced currents. (See Paragraph 23 et seq.).
Other prior devices for moving bottom material are shown and disclosed in the following U.S. Pat. Nos. 3,629,963 (an underwater bulldozer operated from a ship by means of a cable); 3,900,077 (a platform mounted on telescoping legs and having tractor feet on the lower ends thereof for resting on the bottom and a clam shell bucket which can be lowered to the bottom for scooping up quantities of bottom material); and 4,329,793 (a trenching implement suitable for towing on a sea bed to make a trench for a submarine cable or pipeline).